LII and LIII ionization cross sections in gold at very low energies

Salem, S. I.; Moreland, L.D.

doi:10.1016/0375-9601(71)90106-x

Cited by 30 publications

(16 citation statements)

References 6 publications

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“…Electron impact: O, present results; A, Hansen and Flammersfeld [2]; 0, Davis, Mistry, and Quarles [18], corrected for Coster-Kronig transitions; •, Salem and Moreland [19]; ---, present PWBA-C-Ex calculations; --, Coulomb-Born-exchange (CBE) calculations [17].…”

Section: Absolute Cross Sections For Inner Shell Ionization By Leptonmentioning

confidence: 99%

Absolute cross sections for inner shell ionization by lepton impact

et al. 1993

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We report absolute cross sections for K-and L-shell ionization of silver and gold targets, respectively, by lepton (electron, positron) impact in the threshold region. The experiments were performed at the slow positron source TEPOS facility at the linac of the Strahlenzentrum in Giessen. A different behavior of positron and electron impact near threshold was observed. In comparison with theoretical calculations, our results suggest that the differences between electron and positron impact are mainly caused by the acceleration or deceleration of the incident projectile in the target nuclear field.PACS numbers: 34.80.Dp, 34.50.FaThe interaction of an incident projectile with a target atom may give rise to a variety of different elastic and inelastic scattering processes. Ionization of, for example, inner atomic shells by lepton (positron, electron) impact is one of the processes being of fundamental importance for our understanding of collision dynamics. Experimental investigations for electron impact have been reported by many authors (e.g., Ref.[1] and references therein). For positron impact, few absolute cross sections have been reported yet; they were restricted to incident energies Eo> 100 keV (i.e., EQ/I><\, where / is the innershell binding energy) [2,3]. No differences between positron and electron impact were reported in these former experiments. In this paper we report first absolute cross sections for inner-shell ionization by positron (e + ) impact in the threshold regime. We compare these results with cross sections for electron (e~) impact which we have measured with the same apparatus. In the threshold region, we expect different cross sections for positron and electron impact for two reasons: the exchange effect (Ex), important in the ionization by electron impact, and the Coulomb effect (C); the latter effect is caused by the projectile-target nucleus interaction and results in a slowing down (e + ) or acceleration (e ~ ) of the incident projectile.Details of the experimental setup have been described before [4]. Very briefly, it consists of the electron accelerator-based slow positron source TEPOS which delivers intense positron beams of about 6x \0 1 e "Vsec. Positrons with kinetic energy of 2 keV were extracted from the source; they were postaccelerated by a suitable high voltage applied to the target [5,6]. For the measurements with electrons, a corresponding gun was installed in the beamline. The incident energy of the projectiles was varied from 30 keV up to 70 keV for positrons and from 12.3 keV up to 75 keV for electrons. The measurements were performed by detecting characteristic x rays resulting from the inner-shell ionization process. A Si (Li) detector was installed perpendicular to the incident beam. As target we used thin silver (950-5000 A) and gold (800-1000 A) monolayer foils and gold/silver (Au 600 A/Ag 1000 A, Au 1000 A/Ag 1800 A, and Au 1450 A/Ag 3500 A on a carbon backing) multilayer foils. The purpose of these multilayer foils was to measure simultaneously the x-ray yield of...

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Section: Absolute Cross Sections For Inner Shell Ionization By Leptonmentioning

confidence: 99%

Absolute cross sections for inner shell ionization by lepton impact

et al. 1993

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“…In spite of these studies, the body of available data is still scarce and the data are generally affected by important uncertainties. For example, absolute L-shell ionization cross sections have only been reported for Ar [5,6], Kr [7], and Xe [7,8], Au [9][10][11][12][13], W [13,14], and Pt [13]. The situation is even worse for M shells, for which experimental data are extremely rare.…”

Section: Introductionmentioning

confidence: 99%

Measurements of absoluteK-shell ionization cross sections andL-shell x-ray production cross sections of Ge by electron impact

2004

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Results from measurements of absolute K-shell ionization cross sections and L␣ x-ray production cross sections of Ge by impact of electrons with kinetic energies ranging from the ionization threshold up to 40 keV are presented. The cross sections were obtained by measuring K␣ and L␣ x-ray intensities emitted from ultrathin Ge films deposited onto self-supporting carbon backing films. Recorded x-ray intensities were converted to absolute cross sections by using estimated values of the sample thicknesses, the number of incident electrons, and the detector efficiency. Experimental data are compared with the results of widely used simple analytical formulas, with calculated cross sections obtained from the plane-wave and distorted-wave Born approximations and with experimental data from the literature.

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“…we compare results from Scofield and from our Weizsacker-Williams calculations with experimental data [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] for Au, Ni, and A&. [15] for gases or of Ziegler [54] for solids.…”

Section: Discussion Of Cross Sectionsmentioning

confidence: 99%

“…The solid curves are from our Wei zsacker-Wi 1 1 iams calculations, and the broken curves are from Scofield's [32] Born-approximation calculations. The points are from various measurements [33][34][35][36][37][38][39][40][41][42][43][44]. K-shell electron impact ionization cross sections in aluminum and nickle.…”

Section: Goldmentioning

confidence: 99%

Status of electron transport cross sections

Seltzer¹,

Berger²

1982

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This report describes recent developments and improvements pertaining to cross sections for electron-photon transport calculations. The topics discussed include: (1) electron stopping power (mean excitation energies, density-effect correction); (2) bremsstrahlung production by electrons (radiative stopping power, spectrum of emitted photons); (3) elastic scattering of electrons by atoms; (4) electron-impact ionization of atoms.

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LII and LIII ionization cross sections in gold at very low energies

Cited by 30 publications

References 6 publications

Absolute cross sections for inner shell ionization by lepton impact

Absolute cross sections for inner shell ionization by lepton impact

Measurements of absoluteK-shell ionization cross sections andL-shell x-ray production cross sections of Ge by electron impact

Status of electron transport cross sections

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